A Guide to the Ulrich J. Schwarz Radio Interferometer

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1 A Guide to the Ulrich J. Schwarz Radio Interferometer Rocco Coppejans Department of Astrophysics/IMAPP Radboud University Nijmegen September 7, 2015

3 Contents 0.1 Introduction Ulrich Schwarz Characteristics, Properties and Important Information Trouble Shooting A Step-By-Step Guide to the RIF Starting Up Finding your Source Controlling the Telescope How to do a Drift Scan Looking at and Saving Your Data Shutting Down Processing Saved Data The Signal Attenuators How to Zero the Telescope Pointing How to Change the Pointing Osets Additional Notes Elmar's New Software Starting Up Using the Software When You Leave Acknowledgments

4 4

5 0.1 Introduction Figure 1: The RIF. The Astrophysics Department at Radboud University Nijmegen owns our own radio telescope, a two-element radio interferometer, which is located on the roof of the Huygens building. This makes the Radboud University the only university in the Netherlands with its own radio interferometer. The Radio Interferometer (RIF) consists of two 3.5 m dishes that are used for teaching and student projects. The RIF was refurbished in 2011/2012, with both the mechanics and the electronics being completely renewed. After that, the RIF was re-opened on 29 June 2012, where it was renamed the Ulrich J. Schwarz Radio Interferometer. The Netherlands has always been at the forefront of radio astronomy. This started with the 25-meter Dwingeloo Telescope in the fties and sixties followed by the Westerbork Synthesis Radio Telescope, consisting of 14 x 25-meter dishes, in the seventies, and today the Low Frequency Array (LOFAR). The RIF contributes to training of the next generation of Dutch and Dutch-educated radio astronomers and as such helps to maintain the Netherlands's position as a leader on in worldwide radio astronomy Ulrich Schwarz Ulrich J. Schwarz is a pioneer of radio astronomy who moved from his native Switzerland to the Netherlands to be involved in the rst generation of radio telescopes. These included the Dwingeloo telescope and the Westerbork Synthesis Radio Telescope array. He also pioneered interferometry at the Parkes radio telescope in Australia. Through the eorts 5

6 of early pioneers such as Ulrich, the Netherlands is today among the most pre-eminent countries in radio astronomy in the world. After his retirement and move to Arnhem, Ulrich became the guardian of the RIF and supervised the use of the RIF within the physics curriculum at Radboud University. During the move to the new Huygens-building he also provided the inspiration and overview for the refurbishment of the RIF. Credit: The text was adapted with permission from the original ( which was written by Dr. Marijke Haverkorn. 0.2 Characteristics, Properties and Important Information Table 1: Telescope Properties Dish Diameter 3.5 meters Observing Frequency 1.4 GHz Baseline Length 36 meters Primary Beam FWHM 4.5 degrees Raw data rate 40 MB/s Table 2: Dish Pointing Osets Dish RA CAL. Oset DEC CAL. Oset A B Login: account name: rifadmin, password: schwarz Because the software was designed to run continuously and problems with doing so on two dierent accounts simultaneous, all users of the RIF have administrative permissions. PLEASE DO NOT INSTALL OR UN-INSTALL PROGRAMS OR MAKE ANY CHANGES OF ANY KIND TO THE SETTINGS ON THE CONTROL COMPUTER. 3. THE CONTROL SOFTWARE SHOULD NEVER BE CLOSED AND THE CONTROL COMPUTER SHOULD NEVER BE SWITCHED OFF. When you are done observing, please leave the dishes tracking the sun and simply log out of the rifadmin account. This ensures that the dishes are constantly moving, preventing rain water from collecting in them and the dishes from rusting. 4. DO NOT CHANGE THE TIME ON THE CONTROL COMPUTER CLOCK. The time is set to Coordinated Universal Time (UTC) which is used by the telescope control software to point the dishes. You will thoroughly destroy the pointing if you reset the time to local time. 6

7 5. When standing in the control room facing the control computers, you are facing nearly due South. 6. When standing in the control room facing the control computers, dish A is the dish on your right (the Western dish), dish B is the dish on your left (the Eastern dish). 7. If you are trying to observe anything expect the sun or Cassiopeia A, the signal attenuators need to be removed (see Section 0.3.8). 8. When going outside, always take the remote control of the window blinds with you if it's sunny. If the sun shines is on the windows, the blinds will go down automatically, blocking the door. 9. If you spot mistakes in this document, have suggestions or queries, please contact me at r.coppejans@astro.ru.nl or come to speak to me at my desk in room HG Trouble Shooting Below is a list of problems and potential remedies. If none of these solutions solve your problem, please me at r.coppejans@astro.ru.nl or come to speak to me at my desk in room HG Problem: You are not getting any signal from your source. (a) If you are trying to observe a source other than the sun or Cassiopeia A, the attenuators should not be in the signal path. For instructions on how to remove them, see Section Problem: The telescope pointing is o. (a) Check that the computer time is in UTC. UTC time is the local time in Nijmegen minus two hours during summer time (from the rst week of April to the last week of October) and minus one hour during winter time (from the rst week of November to the last week of March). (b) Check that the Zero Oset HA and Zero Oset DA values are set to zero for both dishes in the in the Zero tab of the Axis4 software that is shown in Figure 8. (c) Check that in the Service tab of the Axis4 software the RA CAL. Oset and DEC CAL. Oset values (shown in Figure 9) are set to the values given in Table 2 and that the minus signs (if any) are in the correct position. NOTE: when entering an oset of 30 arcmin to the East, it should be entered as not as (d) If none of the above solutions work, the procedure described in Section can be followed to zero the pointing. 7

8 3. Problem: You cant nd your source. (a) See the solutions to the problems The telescope pointing is o and You are not getting any signal from your source. 4. Problem, the python reduction scripts are failing with the error Segmentation fault (core dump). (a) This is often the result of a le being named incorrectly. Sometimes the slight time dierence in creating the.dat and.cds les can cause the two lenames to dier (by a second) causing the error. To x the problem, the incorrect le name needs to be corrected by hand. 0.3 A Step-By-Step Guide to the RIF In this section, a point-by-point recipe with explanations is presented to lead rst-time users through starting and setting up the RIF, taking data, shutting down and analyzing their data Starting Up 1. Check that the area around the dishes are clear and that there is nothing that the dishes could potentially crash into while moving. This could for example happen if work was done on the dishes and the platform used to reach dishes was not stowed away. 2. Log into the rifadmin account on the control computer using the password: schwarz2012. After successfully logging in you will see the desktop as displayed in Figure NOTE: At the moment all users of the RIF have administrative permissions. PLEASE DO NOT INSTALL OR UN-INSTALL PROGRAMS OR MAKE ANY CHANGES OF ANY KIND TO THE SETTINGS ON THE CONTROL COMPUTER. 4. You can nd your targets, control the telescope and display data using the three icons at the top of the desktop. They are: (a) Axis4: The telescope control software (TCS). (b) RIF_DAQ1.7.vi: The data acquisition, display and initial processing software. (c) Stellarium: Used to nd the coordinates of your target source. 8

Figure 2: The RIF control computer startup screen. 0.3.2 Finding your Source 1. To nd the coordinates of your target, you can search for it in Stellarium. 2. After launching Stellarium, your location on the earth, date and time are shown at the bottom of the screen.

9 Figure 2: The RIF control computer startup screen Finding your Source 1. To nd the coordinates of your target, you can search for it in Stellarium. 2. After launching Stellarium, your location on the earth, date and time are shown at the bottom of the screen. Make sure that this is set to Nijmegen, the current date and the UTC time (local time minus two hours during summer time and minus one hour during winter time). 3. When you click on your target, information on it will be displayed in the top left of the screen. The RA and DEC values of your source (that you need to enter into the Axis4 software) is given as RA/DE (J2000): Controlling the Telescope 1. The telescope is controlled by the Axis4 control software (shown in Figure 3). When you log on, the software should already be running, with the telescope tracking the sun. 2. Note: If you need to start up the software, the message Telescope may not be calibrated at program startup that you get is a precaution and can usually be ignored. The message appears because the software is designed to always run. If it has not been running for a while, the telescope pointing could be o. A guide on how to check the pointing and how to recalibrate the telescope pointing if necessary is given in Section

10 3. At the top of the display, the time (in UTC and LST) and the hour angle (HA) and declination angle (DA) of each dish is shown. 4. Notes: (a) The HA value showed for each dish is not the right ascension (RA) of the dish, but the number of hours that the source is to the East or West of the great circle running from due North, through the zenith to due South. In other words, it tells you how many hours the source is away from passing through its maximum elevation. (b) Similarly, the DA value is how many degrees the source is to the North or South of the North celestial pole and is not the declination (DEC) of the source. A DEC value of -5:00:00 will therefore be displayed as S while a value of 5:00:00 will be displayed as N (c) Although the information for dish A is given on the left hand side of the display, dish A is the dish on your right when you sit in front of the control computer. Similarly the information for dish B is displayed on the right but dish B is on your left. 5. For each dish, there are four tabs Auto Control, Manual Control, Zero and Service that controls the dish. 6. The Auto Control tab: (a) This tab is used to point the dishes at a target and track the target. (b) To slew to a new target, rst make sure that the Tracking HA selector is set to LST and that the Mode is on AUTO. (c) Enter the RA and DEC of your target under the R.A. and DEC. labels and click on the GO TO button to make the dish move to the source. (d) NOTE: When entering values a zero value can never be negative. For example if you want to enter a RA of minus 30 arcmin, it should be entered as not as (e) If the dish is already tracking a target there will not be a GO TO button but a STOP button next to where you enter the RA and DEC values (as is shown in Figure 3). In this case the dish will automatically move to your target as soon as you have entered the coordinates. (f) After you have entered the RA and DEC of the source, the Angle Error indicator will jump to a bigger value and start decrease towards zero as the dish starts slewing towards the new coordinates. As the dish gets closer to the target coordinates, the Angel Error will decrease, reaching a small number (typically less than deg) once the dish has reached the target coordinates. 10

11 (g) The HA and DEC of where the dish is pointing are given in degrees in the Hourangel A/B and Declination A/B indicators. (h) The STOP button can be used at any time to stop the dish from tracking a source. (i) Note that for the reasons discussed above, the R.A., DEC., Hourangel A/B and Declination A/B indicators will dier from the HA and DA values displayed for each dish. 7. The Manual Control tab: (a) To control the dish manually, switch the Mode switch in the Auto Control tab from AUTO to MAN for both the RA and DEC controllers before navigating to the Manual Control tab shown in Figure 4. (b) In the Manual Control tab, you can select in which direction to move the dishes and start them moving by clicking on the START button. The speed of the movement can be controlled using the Speed selector. (c) If one of the limit lights switch on while you are manually moving the dishes, it means that the dish has reached one of its limits and can only move in the opposite direction. (d) Notes: i. Switching mode from AUTO to MAN disables tracking. ii. Please do not forget to switch the Mode back to AUTO before you leave so that the dishes can continue tracking the sun and rain water does not collect in them. 8. The Zero and Service tab: (a) These tabs are used to zero the pointing, see Section At the bottom of the interface there are two sets of indicator lights for each of the dishes. One each for the RA and DEC drives. (a) E limit, W limit, N limit and S limit: indicates that the dish has reached one of its slewing limits. (b) Brake: Indicates that the emergency brake is switched on. If this happens please contact Peter Dolron (p.dolron@science.ru.nl) for technical assistance. (c) End: Indicates that the hard-wired limit switch has been activated. This should not happen and usually indicates that something is very wrong. If this happens please contact Peter Dolron (p.dolron@science.ru.nl) for technical assistance. (d) Zero: Indicates that the dish is at its reference position. If this light switches on during an observation it can be safely ignored, it is only relevant when zeroing the pointing (see Section 0.3.9). 11

12 Figure 3: The Axis4 Auto Control tab. 12

13 Figure 4: The Axis4 Manual Control tab. 13

14 0.3.4 How to do a Drift Scan 1. A drift scan of a source can be done by going to the Zero tab in the software and inputting a value for Zero Oset HA or Zero Oset DA. This introduces an oset, of the number of degrees specied, in the pointing of the dish. 2. You can now do a drift scan of your source by pointing at the source and manually moving the dish in the opposite direction as the input oset, thereby scanning across the source. 3. NOTE: (a) DEC scans are of inferior quality due to a mechanical construction error. (b) Putting in a positive oset value will oset the pointing East or North while a negative value will oset the pointing West or South. 4. Please don't forget to set all the osets to zero again before you leave, otherwise the pointing will be o for the next person Looking at and Saving Your Data 1. The User Interface tab (shown in Figure 5) of the RIF_DAQ1.7.vi program can be used to both look at your data in real time and save it. 2. Note that since the telescope has not been absolutely calibrated, all the units are in analog to digital units and not in Jy. 3. The Observation section: (a) Observation length (s) sets the total observation time in seconds. (b) START and STOP starts and stops the observation. When an observation is in progress, the Acquisition Status indicator will light up. (c) Set Timer starts an observation at a certain time and date. (d) Set interval sets the intervals at which data are taken. (e) N. Interval sets the number of intervals over which data are taken. (f) Every (s) sets the time between intervals. (g) For example Observation length (s) = 1000; N. Interval = 10; Every (s) = 3600 will result in a total observing time of 1000 seconds spread over ten intervals of 100 s each, with each interval starting one hour after the previous one. 4. The Data Processing section: (a) AVG_Times (s) sets the averaging time in seconds. The default value of 1 s is recommended. Due to pointing errors and limitations of the digitizer, using an averaging time of less than one second is not recommended. 14

15 (b) Total Power plots A 2 and B 2 on the y-axis separately. (c) Summed total power plots A 2 + B A 2 B 2 on the y-axis. (d) 2AB plots the correlation 2 A B on the y-axis. 5. The Output section: (a) Time, Hourang and declination plots the variables selected in the Data Processing section as a function of time (in UTC), RA and DEC respectively. (b) Destination File is the path to where the data are saved. Note: Please do not save any data on the C: disk. You can save your data on in the J: disk in a folder with your name. Since space is limited, please delete your data as soon as your are done with it. (c) Raw Data File saves the raw data to disk. Typically at a rate of 40MB/s. (d) Processed Data saves the data columns selected in the Data Processing section to disk. (e) If you don't tick the boxes next to Raw Data File or Processed Data, the data will only be displayed and not saved. 6. While data is being taken and displayed, the scale of the graph can be changed by simply clicking on the maximum or minimum y-value and typing a new value. 7. In the Settings tab, a time delay (in integer multiples of the averaging time) can be introduced between the signal from the two dishes. Inputting an one second shift in dish A means that dish is moved one second ahead (into the future) compared to dish B Shutting Down 1. The Axis4 software should never be closed or the computer shut down. 2. When you are done, point the telescope at the sun and leave it tracking the sun before logging out. When the sun sets, the telescope will stop at the horizon before starting to track it again the next morning. 3. Never leave without the dishes tracking the sun. If the dishes stand still, rain water will collect in them, causing them to rust Processing Saved Data 1. Data is saved in the directory specied in the Output section of the RIF_DAQ1.7.vi program. 2. Note that since the telescope has not been absolutely calibrated, all the units are in analog to digital units and not in Jansky (Jy). 15

16 Figure 5: The RIF_DAQ1.7.viData User Interface tab. 16

17 3. The saved les contain: (a) yyyymmddhhmmss.cds: coordinate le with 11 columns: time in UTC (one column each for HH, MM, SS), HA_A (deg), DEC_A (deg), HA_B (deg), DEC_B (deg), error_ha_a, error_dec_a, error_ha_b, error_dec_b. (b) yyyymmddhhmmss_tpa.txt: The le contains a single column with the total power from dish A in analog to digital units squared. (c) yyyymmddhhmmss_tpb.txt: The le contains a single column with the total power from dish B in analog to digital units squared. (d) yyyymmddhhmmss_ssq.txt: The le contains a single column with the A 2 + B A 2 B 2. (e) yyyymmddhhmmss_fringe.txt: Unknown (f) yyyymmddhhmmss.dat: Contains the raw data in binary format. 4. Running the reduction software on the Linux computer next to the control computer. (a) Log into the Linux computer to the right of the control computer using the password: schwarz2012. (b) NOTE: At the moment all users of the RIF have administrative permissions. PLEASE DO NOT INSTALL OR UN-INSTALL PROGRAMS OR MAKE ANY CHANGES OF ANY KIND TO THE SETTINGS ON THE CONTROL COMPUTER. (c) Create a folder on the desktop using your name as the folder name. Please do not put data any where else than on the Desktop. Data that are not stored on the Desktop will be deleted rst and questions asked later. (d) Copy your data from the control computer into your folder using a ash drive. (e) Copy the reduction scrips and the le _rif.so from the folder titled REDUC- TION_SCRIPTS on the desktop into the folder with your data. (f) You can now run the reduction scrips as described below. 5. Installing the reduction software on your own computer: (a) To install the reduction package on a computer you will need to have the following installed: Python, Numpy and C/C++ and FORTRAN compilers. (b) Copy the folder labeled REDUCTION_SCRIPTS on the desktop to a computer running Linux. (c) Open a terminal and cd into the folder Reduction_Scriptsrif. (d) Type sudo python setup.py install to install the software. (e) Test that the instillation was successful by going into python and typing import rif. If no errors are reported, the instillation was successful. 17

18 (f) Copy the reduction scrips and the le _rif.so from the folder titled Reduction_Scripts on the desktop into the folder with your data. (g) You can now run the reduction scrips as described below. 6. To run the scripts: (a) The scripts need to be in the same folder as your data. (b) In the scripts, change the variable RunNumber to that of your data leaving out the extension. For example RunNumber = (c) The scripts can now be run in Python in the normal way. (d) If you get the error Segmentation fault (core dump) when running the scripts, it could be the result of a le being named incorrectly. Sometimes the slight time dierence in creating the.dat and.cds les can cause the two lenames to dier (by a second) causing the error. To x the problem, the incorrect le name needs to be corrected by hand. 7. Script outputs: (a) crosscorrelate_dual_channel.py: The script makes a plot of real (e.g. cosine; in blue) and imaginary (e.g. sine; in red) parts of the complex normalized cross correlation of the signal as a function of time. (b) plot_averagespectrum.py: The script makes a plot of power as a function of frequency for each of the two dishes. (c) plot_totalpower_dual_channel.py: The script makes a plot of power as a function of time for each of the two dishes The Signal Attenuators If you are trying to observe anything expect the sun or Cassiopeia A, the signal attenuators need to be removed from the signal path. Similarly if you are trying to observe the sun or Cassiopeia A, the signal attenuators need to be in the signal path to prevent the analog to digital converters from saturating. This section describes how to do this. 1. BE VERY CAREFUL WHEN PUTTING THE ATTENUATORS IN THE SIGNAL PATH OR TAKING THEM OUT! THE CABLES CONNECT- ING THE ATTENUATORS ARE STIFF AND HEAVY, IF YOU ARE NOT CAREFUL OR FORCE THE ATTENUATORS IN OR OUT, YOU CAN DAMAGE OR BREAK THE PINS INSIDE THE CONNECTORS. 2. The attenuators are on the wall directly behind and slightly to the right of the telescope control computers and are shown in Figure Each of the dishes have its own attenuator which in its self is made up of two smaller attenuators screwed together. 18

19 Figure 6: Image of the two signal attenuators in the signal path. 4. To remove or insert the attenuators, simply unscrew the signal cables (the black cables at the top) and screw in or screw out the attenuators before reconnecting the signal cables. BE VERY CAREFUL WHEN DOING THIS, THE PINS IN- SIDE THE CONNECTORS CAN BREAK IF THE CABLES ARE BEING PULLED TO ONE SIDE WHILE SCREWING IN OR UNSCREWING THEM. 5. Figure 7 shows a close up view of the attenuators where the attenuator for the left signal path has been removed How to Zero the Telescope Pointing Below a description is given of how to recalibrating the telescope pointing if the pointing is o is given. In theory this only needs to be done once every few months or if the control software have been closed for more than a few days. In practice the telescope tends to decides from time to time that it likes where it is pointing and that it is going to point there no matter what you tell it. This can usually be xed by zeroing the pointing. 1. Before doing anything, make sure that: 19

20 Figure 7: Close up image of the attenuators with the attenuator for the left signal path removed. 20

21 (a) In the Zero tab (shown in Figure 8) the values for Zero Oset HA and Zero Oset DA are set to zero for both dishes. (b) In the Service tab (shown in Figure 9), the values for RA CAL. Oset and DEC CAL. Oset are set to the values given in Table 2 and that the minus signs (if any) are in the correct positions. NOTE: When entering values for the oset a zero value can never be negative. For example an oset 30 arcmin to the East should be entered as not as (c) If any of the above values were wrong, set them to the correct values. The pointing problem should now be xed. 2. If the above values are correct, the telescope pointing can be checked by: (a) Point the telescope at the sun. (b) Plot the total power received by each dish as a function of time as described in Section Each dish should get a signal strength of around 1500 units. If the signal strength is less than 1500 the pointing is possibly o. (c) While continuously plotting the signal strength for each dish, manual move each of the dishes (Section 0.3.3) North, South, East and West. In each case the signal strength should decrease as the dish is moved away from the center of the sun. (d) If the signal strength increases by more than 100 units when you move the dish in a particular direction, it means that the pointing is o and that it needs to be re-calibrated. 3. If the telescope pointing is o, the pointing can be re-calibrated using the following steps: (a) The reason why the pointing slowly deteriorates over time is that the small errors in the encoders that tell the dish where it is pointing add up. Eventually this results in the dish pointing to a dierent place then where it thinks it is pointing (at least this is what happens when the telescope does not deliberately decide to be dicult and point every where except where you want it to point). To correct this the dishes are zeroed by pointing them at a RA and DEC reference position. (b) The dish is zeros when both the Status HA and Status DA Zero lights are switched on at the bottom of the display. (c) Each of the dishes can be moved to its zero position by: i. For HA: A. The HA zero switch is triggered when the dish is pointing due South. In other words you want to move the dish to point the same way that you are facing when sitting in front of the control computer. Turning the dishes to the West will turn them to the right while turning them towards the east will turn them to the left. 21

22 B. Once you have selected the direction in which to turn the dish using the switch labeled as Calibrate Towards click on the START button to start the dish moving. When the dish reaches its reference potion, it will stop moving and the zero light will switch on. C. If the zero light does not switch on, but one of the limit lights does, it ii. For DA: means that you have moved the dish in the wrong direction. In that case move the dish in the opposite direction until the zero light switches on. A. The DA zero switch is located at an elevation of about 60 and is only triggered when moving towards the North. B. Unless the dish is pointing to close to the zenith, set the switch labeled as Calibrate Towards to North and click on the START button to start the dish moving. When the dish reaches its reference potion, it will stop moving and the zero light will switch on. C. If the zero light has not switched on by the time that the dish is pointing close to the zenith, or the dish was initially pointing close to the zenith, stop the dish from moving by clicking on the STOP button (the START button turns to a STOP button when you click on it and vise versa). D. Set the calibration direction to South and start the dish moving. When the dish is pointing close to the horizon, stop the dish, set the calibration direction to North and start the dish moving. When the dish reaches its reference potion, it will stop moving and the zero light will switch on. (d) Once all four the Zero lights are switch on, exit the Axis4 software using the Exit menu next to the Tcp Server! and About! menus in the top left of the screen. This saves the new positions. Do not exit the program using the icon in the top right of the screen. If you do this the new values will not be saved! (e) The pointing should now be xed when you restart the program. (f) After zeroing the dishes remember to put them back into AUTO mode as zeroing will automatically put them into MAN mode that disables tracking. (g) If the pointing is still o, manually move the telescope to point somewhere completely dierent from its zero points and the re-zero the telescope. (h) If this still does not work the procedure described in Section can be followed How to Change the Pointing Osets If zeroing the telescope pointing (as described in Section 0.3.9) does not x the pointing, the pointing can be xed by changing the pointing osets. 22

23 Figure 8: The Axis4 Zero tab. 23

24 Figure 9: The Axis4 Service tab. 24

25 NOTE: This should not be necessary and should not be done unless a major change has been made to the telescope. If you do this, please contact me at r.coppejans@astro.ru.nl or come to speak to me at my desk in room HG so that I can update the manual with the new values. NOTE: If you do this and it turns out it was not necessary, you will screw up the pointing (which will result in me getting loads of s from people that cant nd their sources) I reserve the right to be very angry at you. Hence, make very sure this is necessary before you do this. NOTE: If you do this and dont imidiatly me saying you did it and give me the new zero values, I reserve the right to be insanely angry at you. 1. Before doing anything, make sure that: (a) In the Zero tab (shown in Figure 8) the values for Zero Oset HA and Zero Oset DA are set to zero for both dishes. (b) In the Service tab (shown in Figure 9), the values for RA CAL. Oset and DEC CAL. Oset are set to the values given in Table If both sets of values above are correct, the pointing osets can be changed by: (a) Point the telescope at the sun. (b) While continuously plotting the total power received by each dish as a function of time, change the values for RA CAL. Oset and DEC CAL. Oset for each dish in the Service tab. This will change the pointing oset of each dish with respect to its zero point. (c) As you change the values, the dishes will automatically move to the new position changing the total power received by each of the dishes. The idea is to adjust the oset such that the maximum power is received by each of the dishes. (d) Note that since the beam size is about 4.5 degrees there is no point in trying to get the pointing accuracy to better than 0.5. (e) To save the new calibration values exit the program using the Exit menu next to the Tcp Server! and About! menus in the top left of the screen. Do not exit the program using the icon in the top right of the screen. If you do this the new values will not be saved! Additional Notes 1. Export Data to Your Own Computer (a) Open WinSCP Make a new session on host "helios.astro.kun.nl" with your own login name - don't save your password. It shows the local computer on the left and the remote on the right. Just drag les between folders to copy between computers. 25

26 2. Do Not Delete (a) There is a large data set at J:\20mrt2012 of the Sun at DEC = 0, taking by Peter. This data set can be used to aligned wave fronts exactly, and should not be deleted. 0.4 Elmar's New Software This is notes that explain how use the new software that Elmar wrote and its peculiarities Starting Up 1. On the RIF controle computer: (a) Start the Axis5 program by using the Axis5.exe - Shortcut link on the desktop and set the dishes tracking by clicking on GO TO next to the RA and DEC values of each dish in the Auto Control tabs. (b) Using the Start menu, open Labview. (c) Use the Open Existing tab to open RIF_DAQ_DUAL_CHANNEL_EK_UDP3.vi (d) Run the program by clicking on the arrow in the menu below the File menu. (e) In the area labeled Buer and File Conguration set the Shift value to On the Linux computer: (a) Open a terminal and cd into /home/rifadmin/scheduler. (b) Start Python using the command ipython. (c) Run the scheduler using run -i Scheduler2.py. (d) NOTE: if you get an error saying Error out of memory, restart the computer and repeat the three steps above. (e) Open a web browser and go to Using the Software The web interface is used to point the dishes, do cross-scans, set the scheduling and retrieve data les. To do this, you will need the password Schwarz2012, note that the s is a capital letter. At the time of writing, the only source names that can bet entered into the Point Telescope interface is Crab, BLLac, M87, CygA. You can enter the coordinates of any other source using JHHMM+DDMM where H is RA hours, M is minutes and D is degrees. The web interface will update once a second showing the target, current pointing, and the distance between the target and pointing. If the distance between the target and where the dishes are pointed is less than 0.1 for both dishes, the cross correlations and phases will be shown as a function of frequency on the interface. 26

27 0.4.3 When You Leave When you are done observing, please enable scheduling to ensure that the dishes are always tracking a target. If the dishes stand still, rain water will collect in them, causing them to rust. To enable scheduling go to the scheduling link on the interface and enter 1 into the box labeled Should we run the schedule¾`. The password is Schwarz2012, note that the s is a capital letter. 0.5 Acknowledgments The author would like to thank Pim Schellart, Marijke Haverkorn and Peter Dolron, without their input and patience I could not have written this document. 27

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